Because of the high cross section for neutron capture of the B10 nucleus, boron compounds are promising in tumor therapy. Our objectives in the area of boron hydride chemistry related to this therapy are: (1) by carefully studying the structure and solution behavior of a number of boron hydride derivatives by variable temperature nuclear magnetic resonance (nmr) spectroscopy, we hope to illuminate the way that these and related compounds will behave in therapeutic situations; (2) in the preparative program for producing compounds for structural studies, we expect to make materials which can be screened for therapeutic use; (3) X-ray crystal structure determinations will be performed on key compounds. The compounds planned for study include some in which equivalence of atoms in the nmr spectra indicates fluxional behavior. Among compounds of this nature of interest to us are metal derivatives of BH4 and B3H8 and boron hydride Lewis base derivatives. Variable temperature 1H nmr spectroscopy is invaluable is studies of such compounds and is also very useful in boron hydride derivatives which do not undergo fluxional behavior due to quadrupole induced spin relaxation (thermal decoupling). Our studies of nonfluxional compounds are concentrated on derivatives of the icosahedral carboranes.